A new signal injection‐based method for estimation of position in interior permanent magnet synchronous motors

Abstract : Several heuristic procedures to estimate the rotor position of interior permanent magnet synchronous motors (IPMSM) via signal injection have been reported in the application literature, and are widely used in practice. These methods, based on the use of linear time-invariant (LTI) high-pass/low-pass filtering, are instrumental for the development of sensorless controllers. To the best of authors’ knowledge, no theoretical analysis of these methods has been carried out. The objectives of this note are (i) to invoke some recent work on the application of averaging techniques for injection-based observer design to develop a theoretical framework to analyse the LTI filtering used in sensorless methods and (ii) to propose a new method that on the one hand ensures improved accuracy and on the other hand can be related to the current filtering technique. An additional advantage of the new method is that it relies on the use of linear operators, implementable with simple computations. The effectiveness of the proposed scheme is assessed by experiments on an IPMSM platform driven by a 521 V DC bus with a 5-kHz pulse-width modulation.